1. Field of the Invention
The present invention relates to an improvement of a knob part of an optical connector plug which is structured such as to be shut off by a shutter at a time when the optical connector plug is not fitted to an optical connector adapter and be automatically opened the shutter at a time when the optical connector plug is fitted to the optical connector adapter.
2. Description of the Conventional Art
Conventionally, in this kind of optical connector plug which is provided with the automatically opened and closed shutter, for example, as disclosed in Japanese Unexamined Patent Publication No. 2011-170264 which was previously filed by the applicant of the subject application, a rack and pinion type shutter automatically opening and closing mechanism S is attached to an outer periphery of a front portion of a knob 12 of an optical plug P, the shutter automatically opening and closing mechanism S being structured such as to be normally shut off by an approximately enclosed type shutter at a time when the shutter automatically opening and closing mechanism S is not fitted to an optical connector adapter Q, and be automatically opened the shutter at a time when the shutter automatically opening and closing mechanism S is fitted to the optical connector adapter Q (refer to FIGS. 8, 9, 10 and 11).
The shutter automatically opening and closing mechanism S is installed to the optical plug P in such a manner as to cover an upper side of the sleeve-like knob 12 along a longitudinal direction by attaching a rear stopper guide 22 and an intermediate spring guide 23 to an outer cover 24 which covers a front side of the sleeve-like knob 12 along the longitudinal direction in a polygonal shape so as to freely expand and contract with each other, as shown in FIGS. 8A, 8B, 9A, 9B and 9C. In this case, a grip portion 12a of the knob 12 for gripping the optical plug P protrudes like a rectangular projection shape right and left in a rear end side.
The stopper guide 22 is integrally formed in an upper surface of the grip portion 12a in the rear end of the knob 12, and the spring guide 23 is structured such as to be slidably movable to the upper surface of the stopper guide 22. On the other hand, the outer cover 24 is formed as an approximately rectangular tube shape which is approximately the same shape as an outer periphery of a housing H of the optical connector adapter Q, and is structured such that an extension portion 24a protruding toward a rear side from an upper side thereof can slidably move on the upper surface of the spring guide 23, as shown in FIGS. 10A, 10B, 11A and 11B.
Further, a front side of the knob 12 to which the optical plug P is installed is inserted to an inner portion of the tube of the outer cover 24, and guide projections (not shown) which are provided in a protruding manner in both right and left sides of an upper inner surface of the outer cover 24 are engaged with guide long grooves 31 which are formed along a longitudinal direction in both right and left sides of the upper surface of the knob 12. Accordingly, when the plug P (the knob 12) moves forward in relation to the outer cover 24, the outer cover 24 relatively slides toward the stopper guide 22 side (the rear side of the knob 12) along the guide long grooves 31.
Further, a rack arm (not shown) is arranged in each of inner surfaces in a lower side of right and left side walls of the outer cover 24, and a pinion (not shown) serving as rotary shaft portions of both right and left ends of the shutter is engaged with the rack arm. The rack arm can move back and forth in relation to the knob 12 by fitting to guide portions 41 which are provided in both right and left lower ends of the knob 12 so as to be concaved along a longitudinal direction. Further, on the basis of a back and forth movement of the rack arm, the shutter 21 is automatically opened and closed via the pinion.
As shown in FIGS. 11A and 11B, when the optical plug P is inserted to the housing H of the optical connector adapter Q, the outer cover 24 hits against an inlet of an insertion opening portion of the optical connector adapter Q, whereby the shutter starts opening at the same time that the outer cover 24 starts moving backward. Accordingly, the outer cover 24 moves backward to a position of the stopper guide 22 in a rear portion while compressing a spring 28 together with the spring guide 23. In other words, the optical plug P moves so as to protrude forward from the outer cover 24. In the moving end, a ferrule is inserted to a sleeve holder of the optical connector adapter Q.